By using the half angle formula for and then squaring both sides, we get:

= 1 + cos x

So we have:

2 cos² x + 3 cos x + 1 = 0

(2 cos x + 1)(cos x + 1) = 0

Solving, we get

cos x = − 0.5 or cos x = − 1

Now gives .

However, on checking in the original equation, we note that

but

So the only solution for this part is

Also, cos x = − 1 gives x = π.

So the solutions for the equation are

A check of the graph of confirms these results: